Here’s a list of questions that could be used to help flesh out an NPC. I suggest rolling 3 times on the list and answering the random question.

d20 Roll Question
1 What is a significant event from your past that shaped who you are today?
2 What are your greatest fears or anxieties?
3 What motivates you to achieve your goals?
4 Who are the most important people in your life?
5 What does a perfect day look like for you?
6 What core values drive your decisions and actions?
7 How do you react to stress and pressure?
8 What are your primary skills and talents?
9 What are your short-term and long-term goals?
10 How do you handle failure and setbacks?
11 What are your relationships like with family and friends?
12 How do you express your emotions?
13 What are some of your most notable personality quirks?
14 What habits do you have that might seem strange to others?
15 What is something you enjoy doing that others might find surprising?
16 How do you cope with grief and loss?
17 Where did you grow up and what was your family life like?
18 What is your current occupation or role in society?
19 How do you interact with strangers or new acquaintances?
20 If you could change one thing about your life, what would it be?

If you want more variety, try this table:

d100 Roll Question
1 What is a significant event from your past that shaped who you are today?
2 What are your greatest fears or anxieties?
3 What motivates you to achieve your goals?
4 Who are the most important people in your life?
5 What does a perfect day look like for you?
6 What core values drive your decisions and actions?
7 How do you react to stress and pressure?
8 What are your primary skills and talents?
9 What are your short-term and long-term goals?
10 How do you handle failure and setbacks?
11 What are your relationships like with family and friends?
12 How do you express your emotions?
13 What are some of your most notable personality quirks?
14 What habits do you have that might seem strange to others?
15 What is something you enjoy doing that others might find surprising?
16 How do you cope with grief and loss?
17 Where did you grow up and what was your family life like?
18 What is your current occupation or role in society?
19 How do you interact with strangers or new acquaintances?
20 If you could change one thing about your life, what would it be?
21 What is your biggest regret?
22 How do you unwind after a long day?
23 What is your favorite memory?
24 What is your greatest achievement?
25 Who is your hero or role model?
26 What is your favorite hobby?
27 What is your most prized possession?
28 How do you handle conflict?
29 What is your greatest weakness?
30 What is your favorite place in the world?
31 How do you describe yourself to others?
32 What is your most embarrassing moment?
33 What is your philosophy on life?
34 What are you most passionate about?
35 What are your political views?
36 What is your relationship with money?
37 How do you handle success?
38 What do you think happens after death?
39 What is your biggest pet peeve?
40 What is your favorite book or movie?
41 What is your biggest fear?
42 What motivates you to get out of bed in the morning?
43 What is your favorite food?
44 What is your biggest dream?
45 How do you spend your free time?
46 What do you value most in a friend?
47 How do you deal with difficult people?
48 What is your favorite quote?
49 What is your favorite song?
50 What do you think is your best quality?
51 What is the most challenging experience you have faced?
52 How do you define success?
53 What do you want people to remember you for?
54 How do you feel about taking risks?
55 What is your biggest insecurity?
56 What are you most proud of?
57 What is your idea of a perfect vacation?
58 What are your spiritual beliefs?
59 What do you believe is the meaning of life?
60 How do you handle criticism?
61 What is your favorite time of day?
62 What is your biggest secret?
63 What is the most important lesson you have learned?
64 How do you deal with change?
65 What is your relationship with your parents?
66 How do you handle disappointment?
67 What are your dreams for the future?
68 What is the best advice you have ever received?
69 What is the most spontaneous thing you have ever done?
70 How do you make decisions?
71 What is your favorite childhood memory?
72 How do you deal with stress?
73 What is your proudest moment?
74 What are you afraid of?
75 What do you do for fun?
76 What is your biggest challenge right now?
77 How do you stay motivated?
78 What are your strengths and weaknesses?
79 How do you define happiness?
80 What are your future goals?
81 How do you handle loneliness?
82 What is your greatest ambition?
83 What is your favorite way to relax?
84 How do you approach new opportunities?
85 What do you consider your biggest failure?
86 What is your favorite thing about yourself?
87 How do you express your creativity?
88 What is your most memorable dream?
89 How do you feel about your appearance?
90 What is your favorite season?
91 How do you deal with difficult situations?
92 What are your beliefs about love?
93 What is your biggest passion?
94 What do you do to stay healthy?
95 What do you want to achieve in the next year?
96 How do you handle being alone?
97 What is your favorite sport or physical activity?
98 How do you stay organized?
99 What is your greatest strength?
100 How do you want to be remembered?